1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image by using an electrophotographic method.
2. Description of the Related Art
An image forming apparatus for forming an image by superimposing a white developer image and an another-colored developer image by using an electrophotographic method has been conventionally known. See, Japanese Patent Application Publication No. 2014-032280 (Patent Document 1), FIG. 2 and FIG. 5, for example.
It is difficult to charge a white developer in comparison with developers of other colors, since it contains a much amount of a metal oxide having relatively low electrical resistance. Accordingly, the white developer has properties that it is charged with polarity opposite to normal charge polarity, or that its charge amount is easy to become small. As a result, there is a case where a phenomenon called “fogging” in which the developer is stuck to an area where no image is supposed to be formed is caused.